The present invention relates to the providing of metal electrodes in processes in which electrolytic decomposition is performed by passing an electric current from one electrode to another through an aqueous electrolyte. More particularly, the present invention pertains to the use of metal anodes instead of the historically popular graphite anodes in the electrolysis of aqueous solutions of salt to form chlorine and caustic. Even more particularly, the present invention pertains to the use of electrically-conductive substrates having substantially-insoluble electrically-conductive metal oxide coatings as anodes in a chlor-alkali diaphragm cell.
The problems associated with the use of graphite anodes in such chlor-alkali cells are well known to practitioners of the art. As the graphite wears away, the distance between cathode and anode increases and this causes loss of power efficiency. Furthermore, the undesirable carbon products created by the chemical, electrochemical, and physical depletion of the graphite anodes are substantial enough to create a need for remedy.